<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>后盾人</title>
    <style>
        * {
            padding: 0;
            margin: 0;
        }

        body {
            width: 100vw;
            height: 100vh;
            display: grid;
            grid-template: 1fr/1fr/
        }

        div {
            width: 50px;
            height: 50px;
            background: red;
            align-self: center;
            justify-self: start;
            color: yellowgreen;
            box-shadow: 55px 55px 0 currentColor;
        }
    </style>
</head>

<body>
    <div></div>
</body>

</html>